<!DOCTYPE html>
<html>
<head>
	<title></title>
</head>
<body>
	<script type="text/javascript">
		//计算2的n次幂，n可输入，n 为自然数
		//1 * 2   		2的一次幂
		//1 * 2 * 2		2的二次幂
		//1 * 2 * 2
		var n = parseInt(window.prompt('input'));
		var mul = 1;
		for(var i = 0; i < n; i ++){
			mul *= 2;
		}

		//n的阶乘
		// 5！ = 5 * 4 * 3 * 2 * 1；
		// 4！ = 4 * 3 * 2 * 1；

		var mul = 1;
		for(var i = 1; i <= n; i ++){
			mul *= i;
		} 

		//输入a,b,c三个数，打印出最大的数
		var a = parseInt(window.prompt('input'));
		var b = parseInt(window.prompt('input'));
		var c = parseInt(window.prompt('input'));

		if(a > b){
			if(a > c){
				document.write(a);
			}else {
				document.write(c);
			}
		}else {
			if(b > c){
				document.write(b);
			}else{
				document.write(c);
			}
		}

		//编写一程序，输入一个三位数的正整数，输出时反向输出，如：输入456，输出654

		//f 	s 	t
		//1		1	2	3	5
		//		f 	s 	t
		var n = parseInt(window.prompt('input'));
		var first = 1,
			second = 1,
			third ;

		if(n > 2){
			for (var i = 0; i < n -2; i ++){
				third = first + second;
				first = second;
				second = third;
			}
			document.write(third);
		}else{
			document.write(1);
		}

	</script>

	<script type="text/javascript">
		//100内的质数
		var count = 0;//记能被整除的次数
		for(var i = 1; i < 100; i ++){
			//看看每个i是否是质数
			for(var j = 1; j <= i; j ++){
				if(i % j == 0){
					count ++;
				}
			}
			if(count == 2){
				document.write(i + '')
			}
			count = 0;
		}
	</script>

	<script type="text/javascript">
		var count = 0;
		for(var i = 1; i < 100; i ++){
			for(var j = 1; j <= Math.sqrt(i); j ++){
				if(i % j == 0){
					count ++;
				}
			}
			if(count == 2){
				document.write(i + '')
			}
			count = 0;
		}
	</script>
</body>
</html>